[MC-135506] Experience saves as a short, used as integer

Experience orbs operate on integer values, and players can use vanilla commands to spawn an exp orb with an exact value.

Spawning an orb at 100k is valid, however if that orb is unloaded, the NBT data saves it as a short, corrupting the value.

Fixing is as trivial as changing the NBT set/get calls to Int for Value instead of Short

Related issues

relates to

MC-131290 Enchantments are saved as shorts, but are loaded as and function with integer values

Comments

migrated 2018-08-03T04:03:12Z

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migrated 2018-08-03T04:03:58Z

have I mentioned how much I hate that environment is a text field above description?....

muzikbike 2020-02-16T23:32:37Z

Tested in 20w07a, spawning in experience orbs beyond the 16 bit integer limit seems to spawn orbs with negative values, implying that orbs now use shorts for storing values all the time.

muzikbike 2020-02-17T00:13:30Z

Is this truly invalid? Or was the resolution based on my potentially incorrect comment judging by the other ticket?

marcono1234 2020-02-17T00:13:34Z

In 20w07a (and probably earlier) the value is both serialized and deserialized as short, additionally it is also serialized as short for the ClientboundAddExperienceOrbPacket packet (Mojang name).

migrated 2020-02-17T18:58:41Z

As reported by Connor, that wasn't what was needed to fix it. It needed to be made an int instead to solve the overflow issue.

there is no benefit to try to be conservative on 2 bytes here. This isn't a heavy packet.

marcono1234 2020-02-18T23:13:12Z

Commands read the value as short as well and there appears to be no case where it is possible that during vanilla gameplay an XP orb with an overflowing experience amount is created.
Do you have a way to create such XP orbs (without calling the ExperienceOrb constructor directly)?
Otherwise you could question in general why certain NBT fields are (de-)serialized as something other than int.

migrated 2020-02-19T03:06:37Z

Is it not possible to spawn an entity and supply its nbt data, passing a large int?

Connors comment implies they did.

muzikbike 2020-02-19T13:49:29Z

I haven't tested in 1.13 or earlier.

marcono1234 2020-02-19T20:31:29Z

While it is possible to write an int in the NBT string, the same methods used for deserialization are called so the int is read as short (this applies to all entities and block entities).

/summon minecraft:experience_orb ~5 ~ ~ {Value:32768}

Summons an XP orb with value -32768s.

I will therefore resolve this report as "Invalid". Please let us know if you find a way to create an XP orb with a value higher than 32767 (short max value) without directly calling its constructor.